Lab: Predator Prey Simulation A Simulation of Jackrabbit and Mountain Lion Interactions

Transcription

1 Lab: Predator Prey Simulation A Simulation of Jackrabbit and Mountain Lion Interactions Background: During the 1920s, as the story goes, the people of the northern Arizona and southern Utah wanted to improve hunting in the area known as Kaibab Plateau. In order to provide excellent deer hunting, they slaughtered all predators of deer, mainly the wolves. This allowed the deer population to soar, making the hunting good. Unfortunately, the number of deer taken by the hunters was less than that taken by the wolves. In addition, hunters usually killed the prime deer and not the sick and weak deer. This meant that the deer population was so high when winter struck that the remaining food supply was quickly exhausted. Most of the deer had died of starvation and epidemics before the winter ended. Eliminating the wolves had a much greater impact on the deer population than anyone had ever realized. Animals spend much of their time looking for and consuming food. Some eat plants (herbivores), some eat meat (carnivores), and some eat both (omnivores). Many carnivores obtain their meat by actively hunting other animals. The hunters are known as predators and the hunted animals are known as prey. In this lab, you will do simulation of a predator prey relationship, with owls as predators and mice as prey. This is a simulation that shows the relationship between jackrabbits and mountain lions. By following the directions, you will determine how the population of one species can affect the other species. You may have already studied several types of population graphs, including S curve, J curve and saw tooth curve. You will work in teams to collect your data, but you are individually responsible your own lab report. List the first and last names of you assigned lab partners: Part 1: Question (Purpose or Problem Statement): What type a graphical relationship will result from a simulation of the predator prey relationship? Possible Answers: List three different answers for the question. 1. _ 2. _ 3. _ Chosen Answer: # : Justification:

2 Materials: Large piece of cardboard representing the habitat 100 small yellow or orange square cards representing jackrabbits 1 medium size square blue card representing the mountain lions One copy of the data table for each member of the team Note: Your teacher will demonstrate the first few generations and you will record the data. After that each group collects data based using the numbers of rabbits and mountain lions at that point. Procedure: 1. Place 10 jackrabbit squares evenly separated on the large habitat square. 2. Hold the mountain lion card at least 60 cm above the habitat and drop it. 3. If the mountain lion square lands on any rabbits, whole or part, the rabbit is considered to be eaten and collected in a pile somewhere off the board. 4. Count the eaten rabbits and record this number in your table. 5. Count the remaining rabbits (survivors) and record this in your table. 6. To calculate the number of rabbits for the next generation, multiply the number of surviving rabbits from the previous generation times three. This is the number of rabbits to start the next generation. You need to add sufficient squares to the habitat to equal this number. Remember to first count the number of rabbits remaining before adding new squares. If the total number of rabbits exceeds 100, you can only place 100 rabbits on your habitat. You must assume the others died of starvation or epidemics. 100 is the carrying capacity of rabbits in this habitat. 7. To calculate the number of mountain lions for the next generation, use the following information: Total rabbits eaten is 0 2: no mountain lions survive, 1 mountain lion will migrate in Total rabbits eaten is 3 5: 1 mountain lion starts the next generation Total rabbits eaten is 6 8: 2 mountain lions start the next generation Total rabbits eaten is 9 11: 3 mountain lions start the next generation Total rabbits eaten is 12 14: 4 mountain lions start the next generation Total rabbits eaten is 15 17: 5 mountain lions start the next generation Total rabbits eaten is 18 20: 6 mountain lions start the next generation Total rabbits eaten is 21 23: 7 mountain lions start the next generation Total rabbits eaten is 24 26: 8 mountain lions start the next generation Total rabbits eaten is 24 26: 9 mountain lions start the next generation Total rabbits eaten is 27 29: 10 mountain lions start the next generation (Note: to calculate the number of mountain lions to start the next generation, divide the (total number of rabbits eaten 3) by 3 and discard any remainder Alternative: total rabbits eaten divide by 3 then minus 1 7. Record the number of mountain lions in the last column of your table 8. Add enough rabbits to your habitat to equal the number you have calculated. Be sure to spread the rabbits out as far as possible 9. For each mountain lion in the next generation, you will drop the mountain lion square that many times and pool all the eaten rabbits together.

3 10.If the number of mountain lions reaches zero (all the mountain lions have died) then a new mountain lion will migrate into the habitat. The number of mountain lions never drops below If the number of rabbits at the beginning of any generation is less than 10, add sufficient squares to equal 10 on the habitat. These rabbits entered by migration. Be sure that the rabbits are well dispersed at the start of each generation each time. (The number of surviving rabbits triples at the start of the each generation and the total number of rabbits never drops below 3 at the start of any generation.) 12.Continue the simulation until you have completed 30 generations. Show your data to the teacher and she will decide how many more generations are needed before graphing this information. This must be completed on the first day Once you have completed your data table and have received your teacher s approval, you may continue by creating the necessary graph. This will be a line graph with two lines. This is the one lab that you are allowed to connect the dots. You will need two lines: one for mountain lions and one for rabbits. You will need a legend to tell the lines apart. Use two different colored lines. 14.Write your graph title on the line. 15.What is the independent variable? 16.What units is your independent variable measured in? 17.Write your X axis title based on your answers to 17 and What is the dependent variable? 19.What units is your dependent variable measured in? 20.Write Your Y axis title based on your answers to 19 and What is your largest independent variable? 22.Write your X axis scale between 0 and your answer in 22 on your graph 23.What is the greatest number of animals in your data table? 24.Write your Y axis scale between 0 and your answer in 23 on your graph 25.Get a teacher stamp for your answers above. Teacher Stamp: 26.Plot the rabbit data (second column) on your graph and then connect the dots using a straight edge. Connect your dots using a dark color. 27.Plot the mountain lion data (third column) on your graph and then connect the dots using a straight edge. Connect our dots using a different dark color. 28.Create a legend for your two sets of plotted data. 29.If there is time, have your teacher check your graph. 30.Answer the Summary Questions.

4 Effect of Mountain Lion Predation on Jackrabbit Population Time (Genera tions) Number of Rabbits Caught Number of Surviving Rabbits Number of Rabbit Offspring (Survivors x 3) Total Number of Rabbits Survivors + Offspring Total Number of Mountain lions ([caught rabbits 3]/3)

5 Graph Title: Title: Legend: Title/Units:

6 Summary Questions 1. What is a carrying capacity? 2. Are the carrying capacities of the predator and the prey population the same? Explain: 3. What affects the carrying capacity of prey populations? 4. What affects the carrying capacity of predator populations? 5. What type of graph did you create? 6. Which population always increased first? Why? 7. Which population always decreased first? Why? 8. How long did a cycle of increase and decrease take for jackrabbits? for mountain lions? 9. Which population was almost always in greater numbers? 10. Which population was almost always in smaller numbers? 11. What effects did the rabbit population have on the mountain lion population? 12. What effects did the mountain lion population have on the rabbit population? 13. If a student failed to include a legend, what are three ways you could tell the difference between the mountain lion line and the rabbit line? A. B. C.

7 Part 2: Factors that Can Affect the Jackrabbit and Mountain Lion Predator Prey Cycles Question: What effect do natural and man made factors have on a simulation of the predator prey relationship? Situation Card Selected: Prediction: How will your situation card affect the predator prey graph? Be specific for the jackrabbit population and the mountain lion population Make sketches of your original graph and what you predict will happen in the situation. Be sure to include axes titles and a legend (key). Consider the maximum each population will reach and the time between cycles in your graph Original Graph Predicted Graph Possible Materials:

8 Large piece of cardboard representing the habitat 100 small yellow or orange square cards representing jackrabbits 1 medium size square blue card representing the mountain lions One copy of the data table for each member of the team Situation cards Additional jackrabbit squares Altered habitat cardboard sheets Directions: 1. Obtain a randomly selected situation card from the teacher and obtain the extra materials if need that are listed on the card. 2. Start the simulation as before and continue for 8 generations using a new data table clearly labeled as situation card used. 3. Continue with the simulation following the directions on the situation card and recording the data. 4. Prepare a graph based on the new data table. 5. Prepare a presentation for the class which emphasizes how your particular situation affected the rabbit and mountain lion populations. You can reproduce your graphs on a white board. 6. When each team presents take notes which include the situation, a sketch of their graph overlaying a normal graph and any differences and similarities noted.

9 Time (Genera tions) Effect of Mountain Lion Predation on Jackrabbit Population Situation: Number of Rabbits Caught Number of Surviving Rabbits Number of Rabbit Offspring Total Number of Rabbits Total Number of Mountain lions

10 Graph Title: Title: Legend: Title/Units:

11 Summary of Presentations: Descriptions should include the situation, how the situation was simulated, how the prey and predator populations were affected such as how big and how small the populations were, time for a cycle of each, etc. You must include your own situation also. Presentation 1: Situation Card: Graph: Descriptions: Presentation 2: Situation Card: Graph: Descriptions: Presentation 3: Situation Card: Graph: Descriptions:

12 Presentation 4: Situation Card: Graph: Descriptions: Presentation 5: Situation Card: Graph: Descriptions: Presentation 6: Situation Card: Graph: Descriptions:

13 Summary Questions for Part 2 1. Which situations caused an increase in both the jackrabbit and the mountain lion population? 2. Why? 3. Which situations caused a decrease in both the jackrabbit and the mountain lion population? 4. Why? 5. Which situations caused an increase in the jackrabbit population and a decrease in the mountain lion population? 6. Why?

14 7. Create another situation in which you believe would cause the prey and predator populations to decrease. 8. Explain why you believe this will happen. 9. Create another situation in which you believe would cause the prey and predator populations to increase. 10.Explain why you believe this will happen. 11.In real life, are there any situations in which the prey population and the predator population would not eventually increase or decrease together? (That is one population increases and the other decreases for the long term.) 12.Explain your answer.